Assassin insect considered beneficial

Published: Friday, June 6, 2014 at 07:04 PM.

Question: An insect with long black legs and a red body just stung me. What is it?

Answer: Thank you for sending me this great photo. I encourage all my readers to send me photos of their problem plants, weeds and insects. It is a great aid in the diagnosis of a problem. The insect in question is an immature assassin bug. They have dagger like penetrating beaks. These are predatory insects that feed on other insects. They actually stalk their prey. In that vein, they are considered beneficial. As they get older their stings become more painful and will often leave a whelp. I have seen whelps as big as a quarter.

Question: I spent all day putting stump grindings from a tree around my shrubs and flowers. Now my neighbor tells me this mulch will kill my plants. What should I do?

Answer: When stumps are ground the wood chips become mixed with dirt. There is nothing toxic about this mixture. It can be safely put around shrubs and flowers but a depth of no more than 2 inches. If you stockpile this mulch and it begins to heat up and produce steam (composting) the mulch should be allowed to cool down before putting around plants. Use a pitchfork to dissipate the heat. Do not mix this material into the soil. The fresh wood will reduce the availability of nitrogen in the soil. Although it won’t kill plants, it will turn the leaves yellow.

Question: An insect with long black legs and a red body just stung me. What is it?

Answer: Thank you for sending me this great photo. I encourage all my readers to send me photos of their problem plants, weeds and insects. It is a great aid in the diagnosis of a problem. The insect in question is an immature assassin bug. They have dagger like penetrating beaks. These are predatory insects that feed on other insects. They actually stalk their prey. In that vein, they are considered beneficial. As they get older their stings become more painful and will often leave a whelp. I have seen whelps as big as a quarter.

Question: I spent all day putting stump grindings from a tree around my shrubs and flowers. Now my neighbor tells me this mulch will kill my plants. What should I do?

Answer: When stumps are ground the wood chips become mixed with dirt. There is nothing toxic about this mixture. It can be safely put around shrubs and flowers but a depth of no more than 2 inches. If you stockpile this mulch and it begins to heat up and produce steam (composting) the mulch should be allowed to cool down before putting around plants. Use a pitchfork to dissipate the heat. Do not mix this material into the soil. The fresh wood will reduce the availability of nitrogen in the soil. Although it won’t kill plants, it will turn the leaves yellow.

Question: I forgot to put out crabgrass preventer this spring on my fescue lawn. What can I do to keep the crabgrass out now?

Answer: If you are lucky there may still be some unsold bags for crabgrass preventers still in garden centers. Products such as Crabex, Balan, and Halts do not have fertilizer mixed with them. You can apply these products now. If none can be found, raise you mower height to at least 3 1/2 inches to 4 inches high. This can reduce crabgrass germination by 90%. However, it will not work where the fescue turf is thin.

Question: I have finally received permission from my wife to prune our

azaleas. Is it too late?

Answer: It is not too late. They are generally pruned shortly after they finish blooming. This allows the plant to produce new growth this summer and flower buds for next spring. The longer you wait in the season, the less likely they will bloom next spring. Therefore, if you ever want to prune them again it is imperative they flower next spring. Failure to flower can lead to a permanent ban from ever touching them again. For some husbands this may sound very appealing. At this time of the year you can opt for light pruning to shape them or cut them down to within 18 inches from the ground. It all depends on what condition they are in. If they are tall, spindly, and lost most of their landscape appeal, prune them hard. They will respond with new growth in about 4 weeks if they are healthy. A sick or declining azalea will not respond with much vigor. Pruning has no medicinal value. Those azaleas need to be dug up and disposed of.

Rett Davis is a retired Alamance County Extension Director and a Certified Arborist. You can email your questions to him at